Segmented-pontoon boat



Oct. 12, 1965 G. H. EOWLUS sEGMENTED-PONTOON BOAT Filed Aug, 1, 1965 5 Sheets-Sheet 1.

INVENTOR, 645m/ H. 50M/z. 05

Oct. l2, 1965 G. H. Bom/Lus SEGMENTED--PONTOON BOAT 5 Sheets-Sheet 2 Filed Aug. l

5y ,1f/S ,4770/24/56 HAe/s, MECH, /CPz/SsgLL @K5/QA Oct. l2, 1965 G. H. BoWLus 3,211,126

SEGMENTED-PONTOON BOAT Filed Aug. 1, 1965 3 Sheets-Sheet 5 r FIG. a

Era. 6b

f Fra. 6c

INVENTOR. GLEN/v Bon/Lus 5y H15 Awww/Ys fge/5, MECH, RUSSELL A7524/ United States Patent O 3,211,126 SEGMENTED-PONTOON BUAT Glenn H. Bowlus, 251 Lower Cliff Drive, Laguna Beach, Calif.

Filed Aug. 1, 1963, Ser. No. 299,277 24 Claims. (Cl. 11S-28) My invention relates to boats and more particularly to the propulsion of a boat by drive elements disposed in the water on opposite sides of a propulsion axis. The invention will be exemplied as applied to a boat of the catamaran type but is not limited thereto.

If a single long drive element is disposed in the water to one side of the hull or load-carrying structure of a boat and moved with a component of motion laterally of such drive element by use of a drive means on the loadcarrying structure there will be a reaction force on the latter tending to displace it laterally and opposite to the displacement of the drive element. However if two such drive elements are employed, respectively on opposite sides of the hull or load-carying structure, opposite movement of such elements will cancel the reaction forces and can be made to propel the boat. It is an object of the invention to provide a boat with at least one pair of drive elements in the water on opposite sides of a propulsion axis and to move these drive elements oppositely to induce propulsion of the boat in the direction of such axis.

Such drive elements may be partially or completely submerged in the water. Preferably they are buoyant and are connected to the hull or load-carrying structure to provide buoyant support therefor. It is an object of the invention to move two buoyant drive elements or pontoons in opposition to each other to produce propulsion of a boat. The load carrying structure may be of such `a nature that it will float in case the drive elements or pontoons are retracted, removed or become water logged. In the practice of the invention to be illustrated the buoyant drive elements provide the sole support for the loadcarrying structure connecting them, one object of the invention being the provision of a catamaran-type boat in which the pontoons are oppositely moved to induce propulsion.

Propulsion of the craft can be accomplished by oppositely oscillating the two drive elements or pontoons. It is an object of the invention to mechanically oscillate one drive element or pontoon of a pair in opposition to the other to produce water pressure on submerged surfaces at angles favorable to overcoming drag. A further object is to induce propulsion by moving side-by-side drive elements or pontoons in a manner somewhat related to the swimming motion of two parallel flsh.

Propulsive forces are developed if the two drive elements or pontoons are oscillated by being oppositely displaced laterally while changing the attitude thereof, as by changing the degree or direction of convergence or divergence of the longitudinal axes ,during the lateral oscillation. Likewise propulsive effects can be obtained by suitable lateral flexing of the drive elements or pontoons in opposite directions, using pontoons or drive elements which can be laterally flexed to induce propulsion in the manner related to that in which a fish swims. It is an object of the invention to employ either or both of these propulsive effects in inducing propulsion of a boat. In the preferred practice of the invention both effects are utilized to increase the propulsive effect and it is an object of the invention to oppositely displace and change the curvature of two drive elements or pontoons to induce propulsion of the boat.

In the preferred practice of the invention it is desirable to use drive elements or pontoons that are laterally tlex- 3,211,126 Patented Oct. 12, 1965 ible in a plane generally toward and away from the propulsion axis. It is an object to liex such drive elements or pontoons in such a plane. Another object is to oppositely and laterally displace the two drive elements or pontoons in this or a similar plane. The propulsion axis need not be at the center of the boat. It can be any axis in the propulsion direction in a vertical plane between the two pontoons or drive elements whether at, below or above the deck level of the boat. Multiple pairs of drive elements or pontoons can be employed each with its two elements on opposite sides of the propulsion axis for this pair to increase the propulsive effect. However the invention will be exemplified as employing a single pair of such elements, as in a catamaran, which offers the simplest way of explaining the propulsive principles on which the invention is based.

It is a general object of the invention to provide two laterally flexible or segmented pontoons with a drive means for oppositely flexing these relative to a load-bearing structure connecting them. It is another object of the invention to mount the pontoons on the load-bearing structure to permit lateral movement of the pontoons relative to the structure. A further object is to provide a drive means connected to fore and aft sections of a exible or segmented pontoon to move these sections out of phase with respect to each other. Still a further object is to provide a drive means in which the phase angle between the fore and aft sections can be readily adjusted.

Another object of the invention is to provide a iiexible pontoon made up of a number of sections hinged together about upright axes in the longitudinal plane of the pontoon and to drive these sections to obtain a propulsive effect. These sections may include fore and aft sections with intermediate sections therebetween and with a tail section trailing the aft section. It is an object of the invention to control such a tail section to give a rudder effect. A further object is to provide a resilient means connecting such a tail section to the aft section biasing these sections toward longitudinally aligned positions.

Further objects and advantages of the invention will be evident to those skilled in the art from the following description of a catamaran embodying the principles of the invention.

Referring to the drawings:

FIG. 1 is a plan view of a catamaran embodying the invention, the showing being somewhat fragmentary in that passenger or cargo accommodations are not illustrated for purpose of clarity;

FIG. 2 is a side elevational view of the catamaran;

FIG. 3 is a front view of the catamaran taken as indicated by the line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary view of a portion of the structure as viewed in FIG. 2 illustrating the connection between one pontoon and the load-bearing structure;

FIG. 5 is a top view of an alternative load-bearing structure; and

FIGS. 6a, 6b and 6c diagrammatically show the relative positions of the pontoons at three positions during a cycle of operation, a fourth position in such cycle being shown in dotted lines in FIG. 6c.

'Phe catamaran illustrated includes in general two drive elements or liexible pontoons 10 and 10 respectively on the starboard and por-t sides of a propulsion axis A-A. The pontoons are latt-ached to a hull or load-bearing structure generally indicated by the numeral lf2 `and .are driven by a drive means 14 to induce propulsion of the boat in the direc-tion Iof the arrow l16. The -drive means pnovides means for laterally and oppositely displacing the pontoons wihile changing their longitudinal iaxes in the sense of changing the attitude thereof with respect. to the propulsion axis A-A or flexing different portions of the pontoons to curve such axes -opp'osi-tely, all while the pontoons are in .a body `of water having a surface 18 to provide buoyant support for the load-bearing structure land the load carried thereby.

lEach pontoon `10, is preferably flexible in a plane laterally of its longitudinal axis. As exemplified, each pontoon is flexible in a plane generally toward and away from the propulsion axis A-A of the boat. Flexibility can be imparted in any suitable way but in a catamaran of the sport type lillustrated it is most easily provided by use Iof a segmented pontoon with a number of sections hinged together :about generally rupright axes spaced from each other along the longitudinal axis of the pontoon. As illustrated, the :starboard pont-oon 10 is composed of a fore section 20, an intermediate section Ztl, a rear section 22 and a tail section 23. iM-ore sections or a lesser number can be used. Corresponding sections ofthe port pontoons 10' are designated by corresponding primed numbers.

For simplicity the pontoon sections rare shown as hinged together by hinge pins 26. For example the hinge pin between the fore and intermediate sections 20 and 21 may have its upper portion extending through both fa rearward projection '28 of the pontoon section 20 and ia forward projection 29 of the intermediate pontoon section 21 resting thereon land having a curved forward end 30 (FIGS. 1 and 4) corresponding in shape to the curved rear wall 31 of a top cavity of the fore section 20 in which it turns. Similarly the lower portion of this hinge pin 26 extends through land interconnects ya forward projection 34 of the intermediate pontoon section 21 -overlying a rearward projection 35 of the fore section 20 similarly disposed in a cavity `of t-he in-teimdeiate section. The other -adjacent sections of each pontoon are similarly connected.

Each pon-toon section is .an individual unit, made of buoyant material or of hollow construction with rigid walls suitably spaced and braced. Spaces 36 between the fore and laft ends of `adjacent -sections and through which the hinge pins 26 extend may be blocked by being filled with -a iiexible material such as a suitable mass of sponge rubber. If desired these spaces may be minimized in volume by having the forward end of one section curved throughout its height in the shape of the curved edge 30 with the rearward end of Ithe adjoining or leading section being -shaped throughout its height to correspond with the curvature ofthe Icurved rear wall 311. However the spaces 36 can be left open, as shown, Ias the flow of water therepast is relatively smoot-h and as the open spaces create insignificant turbulence iat reasonable speeds of the boat.

'Each hinge pin can be lheld in place by a collar 38 in the space 36 below the projection 28 and by a clevis 39 above the projection I29. rIlhe clevises 39 serve las a part `of a means for movably connecting :the pontoons to the 'load-'bearing structure i112, shown in FIGS. 1 and 2 as a simple rectangular deck 40. Passenger or load accom- Inodations are not s'hown for purpose of simplicity.

Mounted below the .deck Itransversely thereof are downwardly-open track members 42 spaced from each other a distance equal to the spacing of the hinge pins l26 at the fron-t land rear of the intermedia-te pontoon section 21. A preferred track section is shown in FIGS. 2 :and 4. A carriage 44 is provided for each Iclevis 39 .and is connected thereto by a carriage tongue 45 linked to the clevis by a pin 46. Bach carriage is shown .as having four wheels 47 rolling along the inner surfaces of .the corresponding track member l42, two carriages being disposed in each vtrack member. This structure provides for guided lateral the fore pontoon section `20 has connected to its upper inner edge a drive member, shown as including a drive plate 50 and an attached connecting rod 51. The connecting rod is connected 4by a crank pin 52 to a front starboard crank 54 driven by a gear train '55 of .a gear box i56 mounted below the deck `40. rThe drive plate '50 may be connected to the pontoon section by hinges 57 and to the connecting rod 51 by hinges l58. A diagonal brace `60 has its upper end connected by a 'hinge 61 t-o the underside of the drive plate 50. Its low-er end is connected by a hinge 62 to the fore pontoon :section 20 at la lower level to rigidity the pontoon section and the drive elements. The hinges 57, 61 and 62 here serve largely a connecting function and rigid connections can be substituted.

Corresponding drive elements are shown associated with the fore pontoon section 20 rand are indicated by primed numerals. However in this position it has been found preferable to omit the diagonal brace 160 for a purpose to be later mentioned.

In like manner the aft pont-oon section 22 on the starboard side has a drive plate 70 with a connecting rod 71 connected by a crank pin 7-2 to a rear starboard crank 74- driven by a gear ltrain 75 of a rear gear box 76 below the deck, the drive plate 70 being :connected to the pontoon section .22 by hinges 77 and to the connecting rod 71 by hinges 78. However no diagonal brace is usually employed in this drive connection. lCorresponding drive elements ,are provided for the aft pontoon section 22 on the port side and are indicated by primed numbers. However a diagonal Ibrace y80 is here used, being connected to Ithe underside of the drive plate 70' by a hinge 811 and to the pontoon section 22 at a lower level by a hinge 82.

The use of the diagonal braces 60 and l80 on diagonally opposite pontoons and the omission therefrom as concerns the remaining pontoons gives flexibility to the craft with wave motion or if the .craft is bea-ched. This arrangement prevents the resulting twisting of the craft from placing 'high stresses `on the cranks or crank pins. This is however a supplementary feature and in some instances all of the driven pontoon sections can be similarly braced .to Itheir drive elements.

The `drive means 14 includes a power source -or engine 85 above the deck 40 connected to a transmission 85a which may include an automatic clutch of lthe torque converter type as well as a means for reversing the direction lof rotation of `the -output shaft of .the transmission, here shown as concentric with the input shaft connected to the engine. The output shaft of the transmission is in turn connected by speed-reducing chain-.and-:sprocket drives 86 and 87 to the input shaft 88 of a differential 90 best .shown in FIG l. The input shaft 88 drives a forward Iset of beveled gears 92 through a chain-and-sprooket or -other positive ldrive 94. A vertical shaft 95 (FIG. 2) carries a gear in the gear box .56 meshing with one of the gears of the gear 4train 55. The gear trains 55 and 55 may comprise four gears meshing together as suggested in FIG. 1. The cranks 54 and 54 are thus driven in phase with each other but in opposite angular directions, see FIGS. 6a to 6c.

The differential 90 is of well known construction and contains internal differential gearing driving an output shaft 96 at the same speed as the input shaft 88 but with a phase shift determined by the position of some element of the differential, here shown as the differential housing 97. Means is preferably provided for changing the phase angle between the shafts 88 and 96 to change the phase angle between the fore and aft sections of each pontoon. This can be accomplished as diagrammatically shown in FIG. 1 by ymounting a circular worm gear 98 around the housing 97. A crank 100 carries a worm meshing with the worm gear 98. By turning the crank 100 during operation of the engine 85 the differential housing 97 can be shifted in angular position to change the phase angle of the shaft 96 relative to the shaft 88 and thus change the phase angles of the fore and aft pontoon sections of each pontoon. The connection between the output shaft 96 and the aft sections is through a chain-and-sprocket or other positive drive 101, beveled gears 102 and a vertical shaft 103 entering the rear gear box 76 having the gear trains previously described and adapted to drive the cranks 74 and 74. For purpose of simplicity FIG. 1 shows the forward and rearward cranks with no phase angle therebetween but in the normal operation of the craft the rear cranks will desirably lag the front cranks as will be described. The cranks 74 and 74 are of equal crankearrn length but this may be equal, greater than or less than the crank-arm length of the front cranks 54, 54.

In the embodiment illustrated there is no direct drive to the intermediate pontoon sections 21 and 21. For example the lateral position and attitude of the intermediate pontoon section 21 will be determined by the positions of the hinge pins 26 fore and aft of this section 21. Stated in other Words the intermediate pontoon section 21 floats between the fore section 20 and the aft section 22 and has its position determined by the trailing edge of the fore section and the front edge of the aft section 22. The result is that the sections 20, 21 and 22 can be in alignment (FIG. 1) or the longitudinal axis of the pontoon can be curved to be concave toward the propulsion axis A-A (FIG. 6a) or convex tow-ard this axis (FIG. 6C, full lines). Likewise the attitude of lthe opposed intermediate `sections 20 and 21 will change as suggested in FIGS. 6a, 6b and 6c.

The tail pontoon sections 23 and 23 can be directly driven from the drive means 14 if desired but in the simple craft shown they swing behind the trailing edge of the aft sections 22 and 22 during oscillation thereof being prefer-ably resiliently biased into a predetermined Irelationship therewith. As shown, the fore end of the tail section 23 has secured thereto a rudder bar 105. Cables 106 and 107 having springs 108 and 109 therein are respectively connected to the outer ends of the rudder bar. If these cables are anchored to some portion of the aft section 22, as to a spreader bar 110, the tail section 23 will be resiliently biased toward longitudinal alignment with the aft section 22 and will be displaced from such `alignment by the lateral pressure of the water applied thereto as the aft section 23 oscillataes. In effect the tail section 23 is biased toward the attitude of the aft section 22 but the springs 108 and 109 are not of sufficient tension to maintain exact longitudinal alignment whereby the tail section lags behind the attitude changes of the raft section to which it is connected. The result is that the tail section 23 tends to continue any curvature of the pontoon sections forwardly thereof as will be apparent from FIGS. 6a and 6c.

It is desirable at times to lock the aft section 22 and the tail section 23 together to move .as a unit. This locking is ordinarily desirable during backing up of the craft but may also be employed during forward propulsion. As shown, an auxiliary cable 112 has its ends connected to the outer ends of the rudder bar 105 with its intermediate portion extending around a freely rotating pulley 114 carried by the aft section 22. The auxiliary cable 112 does not per se detract materially from the biasing action of the springs 108 and 109. However :if the tail section 23 is to be locked in some predetermined relation to the aft section 22 a brake member 116 can be moved, by mechanism not shown, into engagement with a portion of the pulley 114 or its cable 112 or both to prevent or retard relative movement between these two pontoon sections.

It is desirable that the starboard and port tail sections 23 and 23 be similarly controlled in relation to the aft `sections 22 and 22 to which they are connected. In this connection the control elements of the port tail section 23 are identical to those described in conjunction with the starboard section and are indicated by ycorresponding primed numbers.

The tail sections 23 and 23' or either of them can also be `made to serve a steering or rudder function. Thus instead of essentially anchoring the forward ends of the cables 106 and 107 they may be end portions of a continuous cable with legs extending forwardly around .paired pulleys 118 mounted on the intermediate section 21, upwardly to and around pulleys 119 and inwardly to a drum lor pulley 120 on a steering shaft 121 to which is connected a steering wheel 122. Likewise the cables 106' and 107 can be unitized to pass over pulleys 118', 119' and 120. The pulleys 119, 119', 120 and 120 are mounted on a forward framework 124 rising from the deck 40 but shown broken away in FIG. 1 for clarity. The vertical portions of the cables between the. pulleys 118 and 119 and between the pulleys 118 and 119 permit oscillation of the intermediate pontoon section 21. These vertical portions merely swing from side to side laterally of the craft as the forward end of the intermediate section 21 oscillates.

By turning the wheel 122 the craft can lbe steered, albeit through the resilient action of the springs 108 and 109. The steering action is produced in effect by changing the tension -in one of the springs relative to the other and thus modifying the biasing action effective even during the steering in causing the 'tail section 23 to swing to some extent as determined by the movement of its attached aft section 22. The steering function can be achieved by having the cables 106 and 107 slide through the spreader bar 110 while the latter is attached to the aft section 22 or by attaching the cables to the spreader bar 110 and permitting the latter to oat or be carried by the cables in which event it will change its -angular position as determined by the relative positions of the cables it connects.

To provide further fiexibility for the craft and compensate for the canting action due to wave motion or beaching the craft the deck 40 may be segmented as shown diagrammatically in FIG. 5. Here the deck is made of deck sections and 130 separated by a small space 132 running diagonally of the craft. The deck section 130 may be secured to the rear track member 42 as before but the forward end of this deck section is exibly connected to the forward track member as lby use of a pin 134 flexibly or pivotally secured to the track member. Similarly the deck section 130 is attached to the forward ftrack member 42 but is flexibly connected to the rear track member as by a pin 134'. Other details are omitted from FIG. 5 for purpose of clarity but it will be understood that the drive means or the steering means will be mounted on one or the -other of the deck sections or may have portions associated with each. The deck sections provide for diagonal flexibility or cant of the craft as for example when the buoyant action on the diagonally opposite pontoon sections 20 and 22 may be greater than on the diagonally opposite pontoon sections 20 and 22.

A desirable sequence of oscillation of the sections of both pontoons is diagrammatically shown in the sequence views of FIGS. 6a to 6c. For purpose of simplicity each combination of a drive plate and crank arm is here shown merely as a drive plate 50, 50', 70, '70' connected to a corresponding crank. The rear cranks '74, 74 are shown lagging the forward cranks 54, 54 by an angle of about 40. This angular lag is preferably between about 20 and about 45 or slightly more for maximum propulsive effect forwardly in the direction of the propulsion axis as later discussed. Different angular deviations of the forward and rear cranks can be employed to produce forward or rearward propulsion and to give different navigation results including a braking action to slow the craft.

Considering the positions of the elements in FIG. 6a as a starting position it will be apparent that the oppositely rotating cranks 54 and 54 are starting to draw the fore sections 20 and 20 together while at the same time increasing the forward convergence of their longitudinal axes toward the propulsion axis. Throughout the sequence views of FIGS. 6u to 6c the pressure exerted on the pontoons by the water at different pontoon positions is indicated by the short lines 150 drawn perpendicular to the pontoon surfaces throughout the area in which this pressure exists. The sequence views of FIGS. 6a to 6c show by the lines 150 only the zones in which the pressure is increased, it being understood that on the opposite side of each pontoon section there will usually be a pressure decrease aiding the propulsion. These pressures have a component in the direction of the propulsion axis and thereby induce propulsion of the craft.

Portions of the propulsive pressure are at times applied to opposite sides of each pontoon, as in FIG. 6a, along different sections thereof. For example as the fore sections 20 and 20 are starting to move toward each other in FIG. 6a to build up pressure on their inner faces the aft sections 22 and 22 and their tail sections 23 and 23 are still moving outwardly under the influence of the cranks 74 and 74 so that the increased pressure is on the outer faces of these pontoon sections. At other times, as in FIG. 6b, the pressure zones on both pontoons are exclusively along the inner surfaces thereof as the cranks 54, 54 and 74, 74 are drawing the pontoons inwardly.

The sequence views of FIGS. 6a to 6c show the cranks in four different positions, 90 apart, and show how in the illustrated embodiment the crank action tends to displace the pontoons while both changing the curvature of the longitudinal axes of the pontoons and changing the attitude thereof. With appropriate crank arrangements the attitude of the pontoons can be changed from one in which the longitudinal axes thereof converge forwardly (FIG. 6b) to an attitude in which these longitudinal axes diverge forwardly or converge rearwardly (FIG. 6c, dotted lines). This is desirable in most instances but propulsive effects can be obtained even if the attitude changes to a lesser degree and if the longitudinal axes of the pontoons do not swing completely across lines parallel to the propulsive axis. By using the crank arrangement shown each pontoon segment is given a sidewise as well as a swinging motion. During forward motion of the vessel any point on any crank-driven segment follows substantially a sinusoidal path opposite to a corresponding sinusoidal path on the opposite side of the propulsion axis. A pure sinusoidal motion can be employed when the pontoon sections are actuated by straight-line systems such as hydraulic cylinders or other straight-line mechanisms to produce propulsion either by inducing curvature of the pontoons or lateral shifting thereof While changing their attitude or both.

The best propulsive effects will be achieved between phase angles of about 20-45 but results will also be usable with phase angles as high as 60. The higher phase angles, eg., about 45 or more, are best during acceleration and the lower phase angles, e.g., in the neighborhood of 20, are best after the craft has been brought up to speed. At a phase angle of or 90 very little or no propulsive effect is obtained with the crank arrangement shown. An action braking the forward motion of the craft can be obtained by change in the phase angle of the cranks during forward motion of the craft. Such change in phase angle to a negative angle of about 45 is useful in inducing reverse movement of the craft. Alternatively such reverse movement can be induced by reversing the driving torque of the engine without shifting to a negative phase angle, as by use of reversing gears in the transmission 85a. Such torque reversal can also be used for braking as it substantially retards any existing forward rnotion of the craft.

It has been found in practice that crafts of this design are extremely efficient. Efficiencies as high as 80% are possible during steady forward movement of the craft but will be somewhat lower during periods of acceleration. Crafts built in accordance with the invention move through the water with no observable wake, evidencing the efficiency with which they operate. They can move through the water essentially noiselessly as compared with a conventional propeller-driven craft and require only a shallow draft and can operate in a canal or river where bottom silt must not be disturbed. The slow speed of oscillation and the absence of high-speed rotating propel- 1ers reduce underwater noise to negligible levels and make it possible to use the craft without being detected by sonar listening devices.

By way of specific example a catamaran 12 feet long and 6 feet wide at the mid-stroke position with pontoon sections two feet high submerged about half this height, when driven by a small 11/2 H.P. engine can attain a speed of better than 3 knots with an oscillation frequency of 25 cycles per second, the forward cranks being set at a 3" radius and the rear cranks at a 4" radius, the phase angle being about 45. For each revolution of the cranks the boat will move forward about 12 feet or about one length for each complete cycle of oscillation. The speed can be changed by adjusting the differential to change the phase angle between the front and rear cranks, usually in coordination with a change in power.

The desirable oscillation frequency of the segmented pontoons decreases as the length of these pontoons increases. For example a craft with 12 foot pontoons operating at approximately 10 knots requires a frequency of only 20 cycles per minute with a phase angle of approximately 20 and with 5" cranks both fore and aft, the required power for a light craft being in the neighborhood of 5 HP. For a craft with pontoons 100 feet long propulsion at the same speed would require a frequency of only about 3 cycles per minute.

The oscillation frequency nor-mally increases with increase in forward velocity, but this increase is offset to sorne extent by a reciprocal factor which is the ratio of distance covered in one complete cycle of oscillation to the length of the boat. A general relationship is expressed by the formula:

F: V/ (YXL) where F is the frequency in cycles per minute, V is the forward velocity in feet per minute, Y is a factor having a numerical value betwen one and five, and L is the length of each pontoon in feet.

It will be apparent to those Skilled in the art that the opposed oscillations of the pontoons of the invention can be produced by means other than the crank mechanisms shown, eg., by hydraulic plungers, steam cylinders or other straight-line mechanisms. It will be apparent also that the invention is not limited to a catamaran-type craft in which the entire weight is supported at all times by the buoyant action of the pontoons. Pontoons or flexible drive elements more deeply submerged in the surrounding water can be used to provide the propulsive effects described whether or not the hull or load-supporting structure is completely above the level of the water. It will be apparent also that the pontoons need not be of the type which are laterally flexible in a horizontal plane, as exemplified. It is however desirable that they be flexible in a plane generally toward and away from the boat or its propulsion axis in which event the reaction forces of the two pontoons are cancelled. The principles of the invention are of broad application and the simplified showings of the present application Will guide those skilled in the art to the design of different and larger craft falling within the scope of the appended claims.

I claim as my invention:

1. In a boat the combination of z a load-bearing structure having a propulsion axis;

a pair of upright drive elements elongated in the direction of said propulsion axis carried by said load-bearing structure in side-by-side relationship in the water respectively on opposite sides of said propulsion axis, each drive element being fiexible between fore and aft ends thereof with the top and bottom porl l axis slidable respectively along said fore and aft tracks;

a segmented pontoon on each side of said propulsion axis, each pontoon having a fore section and an aft section;

means for respectively connecting said fore sections to said fore carriages and said rear sections to said rear carriages; and

drive means operatively connected to said fore sections and said aft sections for moving said pontoons oppositely while moving the fore and aft sections of each pontoon out of phase with respect to each other.

15. A multiple pontoon boat as deiined in claim 14 in which said drive means includes a power source, four cranks driven by said power source comprising a pair of forward cranks and a pair of rear cranks, and crank arm means respectively connecting said forward cranks to said fore sections and said rear cranks to said aft sections.

16. In a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of opposed laterally flexible pontoons respectively on opposite sides of said propulsion axis connected to and providing buoyant support for said load-bearing structure, each flexible pontoon having fore and aft sections movable relatively to each other to curve the longitudinal axis of each pontoon in a plane generally toward and away from said propulsion axis; and

drive means operatively connected to said fore and aft sections of both pontoons for moving the pontoons in opposition to each other while moving the fore an-d aft sections of each pontoon out of phase with each other, said drive means including operating means for moving said pontoons in a cycle in which at successive times said longitudinal axes of said pontoons are concave and later` convex toward said propulsion axis, said drive means and said operating means including means for displaying said pontoons laterally in opposition to each other in a direction toward and away from said propulsion axis while changing the degree of convergence of said longitudinal axes to change the attitude of said pontoons.

t7. In a boat the combination of a loadbearing structure having a propulsion axis;

a pair of segmented drive elements positioned upright in the water in side-by-side relationship respectively on opposite sides of said propulsion axis, each drive element having an upright midplane between fore and aft ends thereof and between the top and bottom thereof, each drive element having a longitudinal axis in said midplane, each drive element being laterally exible between fore and aft ends thereof, each drive element including a plurality of sections hav ing top portions and bottom portions respectively forming the top and bottom of the corresponding drive element and means for connecting said sections` together end to end at their top portions and bottom portions at positions along the longitudinal axis of such drive element;

drive members connected to different sections of one of said drive elements displacing the top portion and bottom portion of the corresponding section substantially equally;

drive means and means for connecting same to said drive members displacing and curving the longitudinal axis of said one drive element relative to said propulsion axis to develop a propulsion force and a lateral reaction force on said load-bearing structure;

other drive members connected to different sections of the other of said drive elements displacing both the top and bottom portions of the corresponding section of said other drive element substantially equal; and

means connecting said drive means to said other drive members displacing and curving the longitudinal axis of said other drive element relative to said propulsion axis to develop another propulsion force and another lateral reaction force on said load-bearing structure equal and opposite to said first-named lateral reaction force.

i8. A boat as dened in claim 17 in which each drive element includes a fore section and an aft section respectively connected to corresponding drive members, said drive means including means for simultaneously changing the phase angles between said fore and aft sections of said two drive elements.

19. A boat as defined in claim 17 in which each drive element includes a fore section and an aft section respectively connected to corresponding drive members and oscillated thereby, said drive means including means for oscillating the aft section of each drive element at a trailing phase angle of about 20-45 relative to the fore section of such drive element.

2Q. A boat as defined in claim 17 in which each section of each drive element is rigid between its fore and aft ends and provides upright pivot axes at such respective fore and aft ends, and including pivot means pivoting adjacent sections together at their top and bottom portions about coaxial fore and aft pivot axes of such adjacent sections.

21. A boat as dened in claim 17 in which each drive element includes a fore section, an intermediate section, and an aft section pivoted together end to end at their top and bottom portions about upright axes spaced from each other along the longitudinal axis of said drive element, and in which said drive members connected to such drive element are connected exclusively to said fore and aft sections thereof whereby the position of said intermediate section at any time is determined exclusively by the existing positions of the aft end of said fore section and the fore end of said aft section.

22. A boat as defined in claim 17 in which one of said sections of each drive element is an aft section, and including a tail section rearward of said aft section pivoted thereto and driven thereby, and means for simultaneously changing the relative positions of said tail and aft sections of said drive elements during operation of said drive means to steer said boat,

23. ln a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of pontoons elongated in the direction of said propulsion axis carried by said load-bearing structure in the water respectively on opposite sides of said propulsion axis, said pontoons providing buoyant support for such load-bearing structure, each pontoon being flexible in a plane generally toward and away from said propulsion axis, each pontoon comprising pontoon sections hinged serially together about upright axes; and

mechanical drive means for oppositely flexing said pontoons in such plane, said drive means flexing said pontoons from end to end thereof and oppositely displacing said pontoons laterally with respect to said propulsion axis while said pontoons are in the water to induce propulsion of said boat.

24. In a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of segmented drive elements respectively in the water on opposite sides of said propulsion axis, each drive element being laterally flexible between fore and aft ends thereof, each drive elements including a plurality of sections and means for connecting said sections together end to end at positions along the longitudinal axis of such drive element, one of said sections of each drive element being an aft section;

drive members connected to different sections of one of said drive elements;

drive means and means for connecting same to said 9 tions of each drive element moving equally during exing of such drive element; and

mechanical drive means for oppositely flexing said drive elements from end to end thereof and oppositely displacing said drive elements laterally with respect to said propulsion axis while said drive elements are in the water to induce propulsion of said boat, said top and bottom portions of each drive element moving equally during such iiexing under the action of said mechanical drive means.

2. In a boat the combination of,

a load-bearing structure having a propulsion axis;

a pair of pontoons elongated in the direction of said propulsion axis carried by said load-bearing structure respectively on opposite sides of said propulsion axis and providing buoyant support for such structure; and

mechanical drive means for equally and oppositely displacing said pontoons laterally relative to such axis while oppositely changing the direction of the longitudinal axes of the pontoons to induce propulsion of said boat.

3. In a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of pontoons elongated in the direction of said propulsion axis carried side-by-side by said loadbearing structure in the water respectively on opposite sides of said propulsion axis and providing buoyant support for said load-bearing structure, each portion being laterally flexible from end to end thereof in a plane generally toward and away from said propulsion axis with the top and bottom portions of each pontoon moving substntially equally toward and away from said propulsion axis during exure of such pontoon; and

mechanical drive means for equally and oppositely oscillating said pontoons toward and away from said axis while equally and oppositely laterally flexing said pontoons from end to end thereof and while equally and oppositely changing the attitude of said pontoons with respect to said propulsion axis to induce propulsion of said boat.

4. In a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of laterally flexible pontoons respectively on opposite sides of said propulsion axis carried by said load-bearing structure and providing buoyant support therefor; and

drive means for oppositely curving said pontoons from end to end thereof while also changing the attitude thereof to converge generally forwardly and later generally rearwardly of said propulsion axis to induce propulsion of said boat.

5. In a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of pontoons carried by said load-bearing structure on opposite sides of said propulsion axis and providing buoyant support for such structure, each pontoon being laterally flexible in a plane generally toward and away from said axis; and

drive means for oppositely displacing said pontoons laterally with respect to said propulsion axis while changing the curvature thereof to be successively concave and convex toward said propulsion axis.

6. In a boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of laterally flexible pontoons respectively on opposite sides of said propulsion axis connected to and providing buoyant support for said load-bearing structure, each flexible pontoon having individuallyrigid fore and aft sections movable relative to each other to curve the longitudinal axis of each pontoon in a plane generally toward and away from said propulsion axis; and

drive means operatively connected to said fore and aft sections of both pontoons for moving the pontoons in opposition to each other while moving the fore and aft sections of each pontoon out of phase with each other, said drive means including operating means for moving said pontoons in a cycle in which at successive times said longitudinal axes of said pontoons are concave and later convex toward said propulsion axis.

7. A multiple pontoon boat as defined in claim 6 in which said drive means and said operating means includes means for moving said pontoons in a cycle in which at successive times said longitudinal axes of said pontoons are concave toward said propulsion axis, converging forwardly theretoward, convex theretoward, and diverging forwardly therefrom.

8. In a multiple pontoon boat the combination of:

a load-bearing structure having a propulsion axis;

a pair of pontoons elongated in the direction of said propulsion axis respectively on opposite sides of said propulsion axis connected to and providing a buoyant support for said load-bearing structure, each pontoon comprising a plurality of sections hinged together about generally upright axes disposed along a longitudinal axis of the pontoon whereby each pontoon is laterally flexible, said sections including a fore section and an aft section;

drive members respectively extending laterally from said fore and aft sections toward said load-bearing structure; and

drive means operatively connected to said drive members of said fore and aft sections of both pontoons for flexing said pontoons and displacing same laterally in opposition to each other, said drive means including operating means for moving said fore and aft sections out of phase with respect to each other.

9. A multiple pontoon boat as defined in claim 8 in which said operating means includes means for changing the phase angle between said fore and aft sectioins.

l0. A multiple pontoon boat as defined in claim 8 in which the movement of said aft section trails the movement of the fore section by a phase angle of about 20-45 11. A multiple pontoon boat as defined in claim 8 in which each pontoon provides a tail section rearward of said aft section and hinged thereto, and including means for resiliently biasing said tail section toward longitudinal alignment with said aft section and means for changing the biasing action of said resilient means on at least one pontoon to steer said boat.

l2. A multiple pontoon boat as defined in claim 8 in which each pontoon provides a tail section rearward of said aft section and hinged thereto, and including means for changing the relative longitudinal orientation of the tail section and aft section of at least one of said pontoons to steer said boat.

13. In a multiple pontoon boat the combination of:

a load-bearing structure having a propulsion axis;

track means carried by said load-bearing structure and extending laterally of said propulsion axis;

carriage means on opposite sides of said propulsion axis slidable along said track means;

a pair of segmented flexible pontoons on opposite sides of said propulsion axis, each flexible pontoon having fore and aft sections at least one of which is connected to a corresponding carriage means; and

drive means operatively connected to at least one of said fore and aft sections for moving the pontoons in opposition to each other while moving the fore and aft sections of each pontoon out of phase with respect to each other to induce propulsion of said boat.

I4. In a multiple pontoon boat the combination of:

a load-bearing structure having a propulsion axis;

fore and aft tracks carried by said load-bearing structure and extending laterally of said propulsion axis fore and aft carriages on each Side of said propulsion 13 drive members displacing and curving the longitudinal axis of said one drive element relative to said propulsion axis to develop a propulsion force and a lateral reaction force on said load-bearing structure;

other drive members connected to dilerent sections of he other of said drive elements;

means connecting said drive means to said other drive a tail section on each drive element rearward of said aft section pivoted thereto and driven thereby; and

means for simultaneously changing the relative positions of said tail and aft sections of Said drive elements during operation of said drive means, said last-named means including a pair of springs resiliently biasing each tail section into longitudinal alignment with its corresponding aft section, and means for changing the relative biasing forces of said springs acting on at least one of said tail sections during movement of a corresponding aft section by said drive means to steer said boat.

References Cited by the Examiner UNITED STATES PATENTS 621,719 3/99 Shann 11S-29 2,156,898 5/39 Giudice 11S-28 3,091,210 5/63 Akutowicz 115-28 FOREIGN PATENTS 467,644 12/51 Italy.

MILTON BUCHLER, Primary Examiner. RALPH D. BLAKESLEE, Examiner. 

1. IN A BOAT THE COMBINTION OF: A LOAD-BEARING STRUCTURE HAVING APROPULSION AXIS; A PAIR OF UPRIGHT DRIVE ELEMENTS ELONGATED IN THE DIRECTION OF SAID PROPULSION AXIS CARRIED BY SAID LOAD-BEARING STRUCTURE IN SIDE-BY-SIDE RELATIONSHIP IN THE WATER RESPONSIVE ON OPPOSITE SIDE OF SAID PROPULSION AXIS, EACH DRIVE ELEMENT BEING FLEXIBLE BETWEEN FORE AND AFT ENDS THEREOF WITH THE TOP AND BOTTOM PORTIONS OF EACH DRIVE ELEMENT MOVING EQUALLY DURING FLEXING OF SUCH DRIVE ELEMENT; AND MECHANICALLY DRIVE MEANS FOR OPPOSITELY FLEXING SAID DRIVE ELEMENTS FROM END TO END THEREOF AND OPPOSITELY DISPLACING SAID DRIVE ELEMENTS LATERALLY WITH RESPECT TO SAID PROPULSION AXIS WHILE SAID DRIVE ELEMENTS ARE IN THE WATER TO INDUCE PROPULSION OF SAID BOAT, SAID TOP AND BOTTOM PORTIONS OF EACH DRIVE ELEMENT MOVING EQUALLY DURING SUCH FLEXING UNDER THE ACTION OF SAID MECHANICAL DRIVE MEANS. 